How add the image alt attribute in every image in the gallery shortcode

I want to add the alt attribute in the output of a shortcode e.g. Now the source code looks like this: <dt class=”gallery-icon landscape”><img width=”150″ height=”84″ src=”//” class=”attachment-thumbnail size-thumbnail” alt=”” srcset=”….. As you can see the attribute alt is empty. How add the image alt attribute in every image in the gallery shortcode?

MarkupInterface interoperability beyond Drupal?

Situation in Drupal 8 Drupal 8 introduces a few classes and interfaces for safe markup: Drupal\Component\Render\MarkupInterface Drupal\Component\Render\FormattableMarkup Drupal\Core\StringTranslation\TranslatableMarkup The purpose is to mark a string as being safe for use in html, without further sanitization. to have the string be lazy-evaluated. The problem seems to be that all of these are specific to Drupal. Use…